High-voltage-current rectification.



J. L. HAYDEN. HIGH. VDLTAGE CURRENT REGTIFIGATION.

APPLICATION FILED JUNE 10, 1907.

1,032,900, Patented Ju1y16,1912.

WITNESSES. I WYENTUH I JUEEPH LR. HAYDEN,

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A TTY JOSEPH L. a. HAYDEN, or sorrnNno'rAnY, NEW YORK, ASSIGNOR 'roGENERAL ELEC- rnIo COMPANY, A con'ronnrron on NEW YORK.

HIGH VOLTAGECURRENT RECTIFICA'IION.

Specification of Letters Patent.

Applicationfiled June 10, 1907. Serial No. 378,157.

To all whom it may concern;

Be it known that I, JOSEPH Ln ROY HAY- DEN, a citizen of the UnitedStates, residing at Schenectady, county of Schenectady, State of NewYork, have invented certain new and useful Improvements inHigh-Voltage-Current- Rectificati'on, of which the following is aspecification.

Vapor rectifiers of themercury vapor type are now being successfullyused for converting. alternating current into, direct current atvoltages suitable for series circuits con-- taining fifty toseventy-five ormore arc lamps. The strains on such vapor rectifiers isconsiderably greater than that on rectifiers operating at lowpotentials, say 110 volts, and many of the phenomena arising inconnection therewith are of a complex nature.

I find that some vapor tubes after operating a considerable time, fromone hundred to several hundred hours, show a deterioration which growsmore and more marked as the tubes age. Thevsymptoms of thisdeterioration are, that static discharges take place and sparks formabout the tube andabout the conductors of the system. Frequently thetube goes out during operation.

Also the tube sometimes starts with difficulty. By heating the tube,mainly the anode arms, before starting, the tube can still be operatedfor some time. Finally, however, it refuses to start at all. The abovementioned sparks or discharges are dangerous to the insulation of thesystem and sometimes puncture the tube.

Although my present invention 15 not limited to any particular theory Iam at present of the belief that the above mentioned phenomena can beexplained in the following way :Mercury oxids are formed duringexhaustion of the tube by the action of'the arc on themer'cury vapor andair left in the tube or leaking into it during exhaustion.

These oxids are dissociated by the cathode spot and are only partiallyre-formedqn' the arc stream. A part of the oxygen so liberated reachesthe graphite anodes and forms- CO. 'The above mentioned chemicalreaction progresses very slowly so that the tube may operate for aconsiderable time without showing any evidence of increase in thegaseswithin the envelop. According to my present belief this gas isgraduallyabsorbed by the anodes when the tube is not in operatlon;

but as soon as; the voltage is put onthe rectifier at starting, the gasis driven out of the anodes, both electro-statically and by heat, andforms a non-conducting gas cushion 1n front of the anodes in. such a waythat the circuit is suddenly interrupted. This causes the static displayabove mentioned. After the tube has once been started this foreignPatented July 16, 1912.

gas gradually diffuses out of the arc stream into the condensingchamber, and thereafter does not interfere so seriously with theoperation of the tube.

Whatever may be the cause of-the peculiar deterioration of the tube andconsequent disturbances in the electrical system, I find that thetrouble can be overcome and the static discharge can be completelyprevented by the means hereinafter described.

Two embodiments of my invention are illustrated in the drawingaccompanying this specification and forming a part thereof.

Figure 1 illustrates a complete rectifier system, and Fig. 2 showsamodified form of discharge pat .Fig. 1 illustrates a mercury rectifier 1of well known type, connected by its anodes 2 and 3 to current supplyingwinding consisting, in this case, of a movable secondary 4 of a constantcurrent transformer. The primary 5 of the transformer is connected to' asource of constant potential alternating cur rent. Suitable reactances 6and? are connected between the rectifier anodes and the transformersecondary 4. A load circuit 9 is connected between the mercury cathode9- eratlonon a potential of several thousand volts. The part of thesystem above described is necessary for converting the energy of theconstant potential alternating current intodirect current of constantvalue for use in the load circuit 8; and the operation of the severalelements of such a system will be readily understood by persons skilledin the art.

According to my present invention, the rectifier tube is shunted by apath having high impedance for the line voltage. Such a path may consistof a non-inductive resistance 10 having a value sutlicient to preventappreciable loss of energy by virtue of the constant potential impressedthereon by transformer secondary 4. The exact value of the resistance isdependent somewhat on the voltage of the system, but onehalf megohm per1000- volts is a very suitable value. The current shunted by such aresistance is only about .002 amperes and that, on a system of thiskind, is negligible. If, now, a film of foreign gas forms around one ofthe anodes and interrupts the high voltage circuit, the system candischarge through the non-inductive resistance 10 without danger to thetube or to the insula tion of the system. The static discharges are ofextremely high voltage and very high frequency, but of small quantity;they therefore discharge safely over the very high noninductiveresistance even though that resistance be of relatively small currentcarrying capacity.

The modification shown in Fig. 2 includes a shunt path consisting ofresistances 11 and 12 connected in series with a condenser 13 andforming a discharge path between the anode leads 14 and 15. This currentcarrying shunt or path is selective in its action and offers aready pathto high frequency currents and a somewhat difficult path to energy ofnormal line frequency. As the static effects in the tube are of highfrequency, they will pass through a condenser of low apparent resistanceeven though the capacity of the condenser is so small as to consume verylittle current at normal frequency. It is advantageous, however, tolimit the flow of current through the condenser 13 in order that thecondenser may not produce oscillations and disruptive discharges bycoaction with the self induction ofthe circuit; this can be effected byuse of the resistances 11 and 12. These resistances need not be largeand can easily be made of such a value as to give a free discharge tothe static electricity while preventing the condenser from producingoscillations.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,-

1. The combination of 'a vapor electric device having a plurality ofanodes, means for supplying electrical energy at high potential to saidanodes, and a shunt of high impedance for current of normal frequencyconnecting said anodes to aiford a discharge path for static chargesdeveloped during the normal operation of said device.

2. The combination of a vapor electric device having a cathode, aplurality of anodes, a source of energy connected across said anodes,and a discharge shunt of low inductance and high resistance connectedacross said anodes.

3. The combination of a vapor rectifier having anodes, a high voltageload circuit receiving current from said device, a source of energyconnected to said anodes, and a shunt for static discharge direct-1vconnecting said anodes, said shunt having a high impedance for currentof normal frequency.

4. The combination of a constant current transformer, a vapor rectifierhaving anodes connected therewith, a series load circuit connectedbetween said rectifier and said transformer, and a non-inductive shuntconnected between the anodes of said rectifier to equalize staticcharges on said anodes said shunt having high impedance for current ofnormal frequency and potential.

5. The combination with a vapor electric device having a plurality ofanodes and a cathode, of a static discharge shunt connecting said anodesand including a capacity reactance.

6. The combination of a vapor electric device, having a plurality ofelectrodes of the same polarity, means for supplying current to saiddevice, and a non-inductive discharge shunt connected between saidelectrodes, for dissipating static charges accompanying the operation ofthe device.

7. The combination of a vapor electric device having a plurality ofanodes and a cathode. of a discharge shunt connected between the saidanodes and including a condenser and aresist-ance.

8. The combination with a vapor electric device having a cathode and aplurality of anodes, means for supplying current to said anodes, and ashunt of low inductance for the discharge of static accumulationsconnected between said anodes, said shunt offering high impedance tocurrent of normal frequency and voltage.

9. The combination of a transformer winding, a. load circuit, a vapordevice having anodes connected to said winding and a cathode connectedto said load circuit, a connection from said loadcircuitto said winding,and means for relieving excessive potential stress connected betweensaid anodes.

10. The combination of a vapor device having a plurality of electrodesof the same polarity, a current supplying winding connected to bothelectrodes and a current carrying shunt between said electrodes adaptedto discharge static charges thereon.

11. The combination of a vapor device having a plurality of anodes and acathode, means for supplying current to said anodes, and a currentcarrying shunt for relieving static strains developed during the normaloperation of the device.

In witness whereof, I have hereunto set my hand this 8th day of June,1907.

JOSEPH L. R. HAYDEN.

Witnesses:

BENJAMIN B. HULL, MARGARET E. WOOLLEY.

